Xanthine compounds such as theophylline, pentoxifylline and propentofylline have been widely used for the treatment of respiratory tract disease or brain dysfunction. Severe adverse reactions are frequently induced by the administration of these compounds. Examples of the adverse reactions are, for example, cardio-excitatory activity such as cardiopalmus or tachycardia; central activity such as convulsion or headache; and gastrointestinal activity such as nausea or emesis.
U.S. Pat. No. 4,883,801 discloses xanthine derivatives as pesticidal and pestistatic agents. Related xanthine derivatives have been disclosed as intermediates, without pharmacological activity, in EP-A-0369744, WO-A-92/05176, EP-A-0389282 and WO-A-94/00452.
EP-A-0435811 discloses xanthine derivatives as phosphodiesterase inhibitors. Further xanthines are disclosed in WO-A-9323401.
Phosphodiesterases (PDE) and Tumour Necrosis Factor (TNF), their modes of action and the therapeutic utilities of inhibitors thereof, are described in WO-A-9720833.